Okay, so I still don't know why rendering is just so slow (though
migrating away from item translations did help!), but I can at least
cache entire closet lists as a basic measure.
That way, the first user to see the latest version of a closet list
will still need just as much time to load it… but *only* the ones that
have changed since last time (rather than always the full page), and
then subsequent users get to reuse it too!
Should help a lot for high-traffic lists, which incidentally are likely
to be the big ones belonging to highly active traders!
One big change we needed to make was to extract the `user-owns` and
`user-wants` classes (which we use for trade matches for *the user
viewing the list right now*) out of the cached HTML, and apply them
after with Javascript instead. I always dislike moving stuff to JS, but
the wins here seem. truly very very good, all things considered!
I've been doing this manually via email for a long time,
since building new stuff in the logged-in world was a pain in the old env.
But now here we are! Finally, finally :)
